Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Chapter 18: TWO CLASSES OF CHEMICAL REACTIONS

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley This lecture will help you understand: Acids Donate Protons, Bases Accept Them Relative Strengths of Acids and Bases Acidic, Basic, and Neutral Solutions Acidic Rain and Basic Oceans Losing and Gaining Electrons Harnessing the Energy of Flowing Electrons Electrolysis Corrosion and Combustion

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acids Donate Protons, Bases Accept Them

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acids Donate Protons, Bases Accept Them

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acid A chemical that donates a hydrogen ion, H + Base A chemical that accepts a hydrogen ion, H + Acids Donate Protons, Bases Accept Them

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley The hydrogen atom H

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley The hydrogen atom H

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley The hydrogen atom H

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley The hydrogen atom H

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley The hydrogen atom H

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley The hydrogen atom H

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley The hydrogen atom H

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H+H+ The hydrogen ion proton

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley BaseBase AcceptsAccepts AcidAcid DonatesDonates

H2OH2OHCl +

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H2OH2OHCl +

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H3O+H3O+ Cl – +

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H3O+H3O+ Cl – H2OH2OHCl ++

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H3O+H3O+ Cl – H2OH2OHCl ++

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H3O+H3O+ Cl – H2OH2OHCl ++ donordonor acceptoracceptor

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H3O+H3O+ Cl – H2OH2OHCl ++ (acid)(base)

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H2OH2ONH 3 +

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H2OH2ONH 3 +

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – +

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley H2OH2ONH 3 +

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – +

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 ++

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 ++

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 ++ donordonor acceptoracceptor

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 ++ (acid)(base)

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 ++

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 ++

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 + (acid)(base) +

Copyright © 2007 Pearson Education, Inc., publishing as Pearson Addison Wesley NH 4 + OH – H2OH2ONH 3 ++ (acid)(base)(acid)(base)

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley When water behaves as an acid, what does it lose? A.A hydrogen ion. B.A hydrogen atom. C.An electron. D.Water can’t behave as an acid. Acids Donate Protons, Bases Accept Them CHECK YOUR NEIGHBOR

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley When water behaves as an acid, what does it lose? A.A hydrogen ion. B.A hydrogen atom. C.An electron. D.Water can’t behave as an acid. Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley When water behaves as a base, what does it gain? A.A hydrogen ion. B.A hydrogen atom. C.An electron. D.Water can’t behave as an acid. Acids Donate Protons, Bases Accept Them CHECK YOUR NEIGHBOR

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley When water behaves as a base, what does it gain? A.A hydrogen ion. B.A hydrogen atom. C.An electron. D.Water can’t behave as an acid. Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. Molecule AMolecule B H O H H + H O H H O H O H – Acids Donate Protons, Bases Accept Them CHECK YOUR NEIGHBOR

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. Molecule AMolecule B H O H H + H O H H O H O H – Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. Molecule AMolecule B H O H H O H Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. Molecule AMolecule B H O H H O H Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. Molecule A H O H H+H+ O H – Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. Molecule A H O H H+H+ O H – Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. Molecule A H O H H+H+ O H – Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Which water molecule is behaving as an acid, and which is behaving as a base? A.Molecule B as a base; Molecule A as an acid. B.Molecule B as an acid; Molecule A as a base. C.Both Molecules A and B are behaving as acids. D.Both Molecules A and B are behaving as bases. + H O H H O H – Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Salt: An ionic compound formed from the reaction of an acid and a base. Acids Donate Protons, Bases Accept Them

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Salt: An ionic compound formed from the reaction of an acid and a base. Acids Donate Protons, Bases Accept Them

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Salt: An ionic compound formed from the reaction of an acid and a base. Acids Donate Protons, Bases Accept Them

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley What salt forms from the reaction of hydrogen chloride, HCl, with potassium hydroxide, KOH? A.KCl B.H 3 OCl C.KOH 2 D.KOH 2 Cl Acids Donate Protons, Bases Accept Them CHECK YOUR NEIGHBOR

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley What salt forms from the reaction of hydrogen chloride, HCl, with potassium hydroxide, KOH? A.KCl B.H 3 OCl C.KOH 2 D.KOH 2 Cl Explanation: The K + from the KOH combines with the Cl – from the HCl. Acids Donate Protons, Bases Accept Them CHECK YOUR ANSWER

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Relative Strengths of Acids and Bases Strong acids and bases ionize completely in water.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Relative Strengths of Acids and Bases Strong acids and bases ionize completely in water.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Weak acids and bases do not ionize completely in water. Relative Strengths of Acids and Bases

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Weak acids and bases do not ionize completely in water. Relative Strengths of Acids and Bases

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Relative Strengths of Acids and Bases

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic, Basic, and Neutral Solutions Water can behave as an acid or a base.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Water can behave as an acid or a base. In pure water, for every one hydronium ion, H 3 O +, formed, there is a hydroxide ion, OH –, formed. Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Water can behave as an acid or a base. In pure water, for every one hydronium ion, H 3 O +, formed, there is a hydroxide ion, OH –, formed. So in pure water, [H 3 O + ] = [OH – ] = M = 10 –7 M. Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Water can behave as an acid or a base. In pure water, for every one hydronium ion, H 3 O +, formed, there is a hydroxide ion, OH –, formed. So, in pure water, [H 3 O + ] = [OH – ] = M = 10 –7 M. Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Water can behave as an acid or a base. Add hydronium ions, H 3 O +, and the solution is “acidic,” Add hydroxide ions, OH –, and the solution is “basic.” Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley As sodium hydroxide, NaOH, is added to water, the hydroxide ion, OH –, concentration A.increases. B.decreases. C.remains the same. Acidic, Basic, and Neutral Solutions CHECK YOUR NEIGHBOR

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley As sodium hydroxide, NaOH, is added to water, the hydroxide ion, OH –, concentration A.increases. B.decreases. C.remains the same. Explanation: The bond between sodium and oxygen is ionic. When dissolved in water, it separates into sodium ions and hydroxide ions, much like sodium chloride, NaCl, separates into sodium and chloride ions. Acidic, Basic, and Neutral Solutions CHECK YOUR ANSWER

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley pH is a measure of the concentration of hydronium ions, H 3 O +. Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley pH is a measure of the concentration of hydronium ions, H 3 O +. pH = –log [H 3 O + ] Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley pH is a measure of the concentration of hydronium ions, H 3 O +. pH = –log [H 3 O + ] For pure water: pH = –log (10 –7 ) pH = –(– 7) pH = 7 Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley pH is a measure of the concentration of hydronium ions, H 3 O +. pH = –log [H 3 O + ] For pure water: pH = –log (10 –7 ) pH = –(–7) pH = 7 What is a log? Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. Quiz Time What is the log of 10 2 ? Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is 3. Quiz Time What is the log of 10 2 ? Log 10 2 = 2 (the power to which 10 is raised) Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = 1000 Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = 100 Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = 10 Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = –1 = 0.1 Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = –1 = –2 = 0.01 Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = –1 = –2 = –3 = Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = = ? 10 –1 = –2 = –3 = Three zeros Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = = ? 10 –1 = –2 = –3 = Two zeros Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = = ? 10 –1 = –2 = –3 = One zero Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = = 1 10 –1 = –2 = –3 = Zero zeros! Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = = 1 10 –1 = –2 = –3 = Quiz Time Log 1000 = ? Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = = 1 10 –1 = –2 = –3 = Quiz Time Log 1000 = ? Log 10 3 = Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = = 1 10 –1 = –2 = –3 = Quiz Time Log 1000 = ? Log 10 3 = 3 Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = = 1 10 –1 = –2 = –3 = Quiz Time Log 1 = ? Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = = 1 10 –1 = –2 = –3 = Quiz Time Log 1 = ? Log 10 0 = Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = = 1 10 –1 = –2 = –3 = Quiz Time Log 1 = ? Log 10 0 = 0 Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = = 1 10 –1 = –2 = –3 = Quiz Time Log 10 – 7 = Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The “log” of a number is simply the power to which ten is raised. The log of 10 3, for example, is = = = = 1 10 –1 = –2 = –3 = Quiz Time Log 10 – 7 = – 7 Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley pH = –log [H 3 O + ] For acidic water pH < 7, for example: pH = –log (10 –5 ) pH = –(–5) pH = 5 Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley pH = –log [H 3 O + ] For basic water pH > 7, for example: pH = –log (10 –9 ) pH = –(–9) pH = 9 Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic, Basic, and Neutral Solutions

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic Rain and Basic Oceans Acid rain has a pH lower than 5. 2 SO 2 (g) + O 2 (g)  SO 3 (g) SO 3 (g) + H 2 O (l)  H 2 SO 4 (aq)

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic Rain and Basic Oceans Acid rain has a pH lower than 5. SO 2 released from burning coal and oil. 2 SO 2 (g) + O 2 (g)  SO 3 (g) SO 3 (g) + H 2 O (l)  H 2 SO 4 (aq)

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic Rain and Basic Oceans CO 2 levels in atmosphere rising CO 2 (g) + H 2 O (l)  H 2 CO 3 (aq)

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic Rain and Basic Oceans

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic Rain and Basic Oceans

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acidic Rain and Basic Oceans

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Losing and Gaining Electrons Acid–Base reactions: transfer of proton

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acid–Base reactions: transfer of proton Oxidation-Reduction reactions: transfer of ??? Losing and Gaining Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Acid–Base reactions: transfer of proton Oxidation-Reduction reactions: transfer of electron Losing and Gaining Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oxidation: The loss of an electron Losing and Gaining Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oxidation: The loss of an electron 2 Na 2 Na e – Losing and Gaining Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oxidation: The loss of an electron 2 Na 2 Na e – Reduction: The gain of an electron Losing and Gaining Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oxidation: The loss of an electron 2 Na 2 Na e – Reduction: The gain of an electron Cl e – 2 Cl – Losing and Gaining Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oxidation: The loss of an electron 2 Na 2 Na e – Reduction: The gain of an electron Cl e – 2 Cl – “Leo” “Ger” Losing and Gaining Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Oxidation: The loss of an electron 2 Na 2 Na e – Reduction: The gain of an electron Cl e – 2 Cl – “Leo” “Ger” (Leo the lion went “Ger”) Losing and Gaining Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley 2 Na + Cl 2 2 Na Cl – Losing and Gaining Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Losing and Gaining Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Losing and Gaining Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley What element within the reactants is oxidized in the following equation, and what element is reduced? I Br –  2 I – + Br 2 A.Iodine, I, is oxidized, while the bromine ion, Br –, is reduced. B.Iodine, I, is reduced, while the bromine ion, Br –, is oxidized. C.Both the iodine, I, and the bromine ion, Br –, are reduced. D.Both the iodine, I, and the bromine ion, Br –, are oxidized. Losing and Gaining Electrons CHECK YOUR NEIGHBOR

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley I Br –  2 I – + Br 2 A.Iodine, I, is oxidized, while the bromine ion, Br –, is reduced. B.Iodine, I, is reduced, while the bromine ion, Br –, is oxidized. C.Both the iodine, I, and the bromine ion, Br –, are reduced. D.Both the iodine, I, and the bromine ion, Br –, are oxidized. Explanation: Note how the iodine gains a negative charge, while the bromine loses the negative charge. What element within the reactants is oxidized in the following equation and what element is reduced? Losing and Gaining Electrons CHECK YOUR ANSWER

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Harnessing the Energy of Flowing Electrons Electric currents generated by oxidation- reduction reactions.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Harnessing the Energy of Flowing Electrons Electric currents generated by oxidation- reduction reactions. Useful for: –Batteries –Fuel cells

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Harnessing the Energy of Flowing Electrons Ions must be able to flow to generate a current.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Harnessing the Energy of Flowing Electrons A salt bridge allows this to happen.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Harnessing the Energy of Flowing Electrons A battery is a self-contained voltaic cell.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The positive electrode is the cathode, where reduction occurs. Harnessing the Energy of Flowing Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley The positive electrode is the cathode, where reduction occurs. The negative electrode is the anode, where the oxidation occurs. Harnessing the Energy of Flowing Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Harnessing the Energy of Flowing Electrons Several types of batteries: –Dry cell –Alkaline –Rechargeable NiMH Lithium

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Fuel cells convert the chemical energy of a fuel into electrical energy. Harnessing the Energy of Flowing Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Harnessing the Energy of Flowing Electrons

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Electrolysis Electrolysis uses electrical energy to produce chemical change.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Electrolysis Electrolysis uses electrical energy to produce chemical change. Examples: –Recharging your car battery –Purifying metal ores

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Electrolysis

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Corrosion and Combustion

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Corrosion and Combustion Corrosion The process whereby a metal deteriorates through oxidation-reduction reactions.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Corrosion and Combustion Corrosion The process whereby a metal deteriorates through oxidation-reduction reactions. It can be prevented by coating the metal with zinc, which oxidizes first.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley Corrosion and Combustion Combustion An oxidation-reduction reaction between a nonmetallic material, such as wood, and oxygen.

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley One of the products of combustion is water. Why doesn’t this water extinguish the combustion? A.While areas of combustion are being extinguished, new areas are combusting. B.Combustion only produces microscopic amounts of water. C.The chemical combustion reaction is happening too fast for the water to have an effect on the fire. D.This water is in the gaseous phase and merely floats away. Corrosion and Combustion CHECK YOUR NEIGHBOR

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Addison-Wesley One of the products of combustion is water. Why doesn’t this water extinguish the combustion? A.While areas of combustion are being extinguished, new areas are combusting. B.Combustion only produces microscopic amounts of water. C.The chemical combustion reaction is happening too fast for the water to have an effect on the fire. D.This water is in the gaseous phase and merely floats away. Explanation: Carefully place your hand over a campfire, and you can feel the greater humidity as water vapor escapes. Corrosion and Combustion CHECK YOUR ANSWER